1. Field of the Invention
The present invention relates to a method for operating a bus system, and particularly a method for the switching of participants of a bus system from a first state with reduced energy consumption to a second state with increased energy consumption relative to the first state.
2. Description of the Prior Art
Manufacturer of automobiles are subjected to ever more restrictive demands to minimize the CO2 emissions of automobiles. One approach for reduction of pollutant emission in vehicles resides in the introduction of partial communication networks in vehicles wherein those functions which are not required (i.e. control devices or bus participants) will be switched off and, when required, will be temporarily reactivated. This idea is not new and has been described e.g. in DE 198 09 726A1, DE 103 58 584 A1, EP 0 870 648 B1, WO 03/104037 A1 and WO 2006/003540 A1; up to now, however, the above approach still lacks technically implementable and commercially attractive realizations.
From FR 2 917 555 A3, there is known a method for the switching of participants of a bus system from a first state with reduced energy consumption to a second state with increased energy consumption relative to the first state, wherein, for communication between the participants of the bus system, data frames are transmitted which comprise, inter alia, a message identification field. In this method, each participant, for switching from the first state to the second state, will react on data frames with respective predetermined data contents in the message identification field, wherein, in the bus system, for selective switching of a participant from the first state to the second state, those data frames will be transmitted on whose message-identification-field contents the selectively addressable participant reacts.
In present-day solutions, the users are confronted with limitations in regard to those messages to be transmitted via the communication network which are available for temporary selective reactivation of the bus participants. An example of such limitations is the CAN bus according to BOSCH: “CAN Specification version 2.0”, INTERNET CITATION, 1991, XP002156917. The messages available for the wakeup function are mostly “hard”-coded in the bus participants, notably in the form of a “pattern” on which a reaction will occur while, however, the wakeup reason/source cannot be identified. Disadvantageously, also introducing further discrete “patterns” would merely allow for rather modest improvements.
It is an object of the invention to provide a method for the switching of participants of a bus system from a first state with reduced energy consumption to a second state with increased energy consumption relative to the first state, wherein this method shall allow for larger flexibility and make it possible to use messages across and beyond the network.